Making water out of thin air

Could a wind turbine that sucks water out of the air supply enough water for the whole world? (Image: iStockphoto)

A wind-driven device could provide an unlimited water supply by harvesting water from the air, says its Australian inventor.

But critics are asking if it's too good to be true.

Dr Max Whisson, a retired medical specialist turned inventor, says he has designed a highly efficient wind turbine that can run a refrigeration system to cool air and condense moisture from it.

"The wind carries in the water and [provides] the power required to separate that water from the wind," says Whisson, who is based in Perth.

He says there is a huge amount of water in the atmosphere that is replaced every few hours. This means the whole world could just use water from the air without disrupting the environment.

Whisson says the system would even harvest significant amounts of water in areas with low humidity.

He says a 4 metre square device could extract an average 7500 litres of water a day.

In his design, moisture-laden air enters the system and is cooled by a drop in pressure behind the wind turbine blades, says Whisson.

The air then flows into a chamber containing refrigerated metal plates covered by a non-wettable surface that causes water droplets to run off immediately into a collection point.

Could it work?

Full technical details of the design are not available but at least one mechanical engineer is sceptical.

"I have found in general that inventors tend to enormously overstate the capacities of their devices. They just have a very rosy outlook on what their devices will do," says mechanical engineer Professor John Reizes, an adjunct professor at the University of New South Wales.

"It's not until you've made one that you discover all the problems."

Whisson's latest wind turbine design (Image: Max Whisson)

Reizes, who specialises in heat transfer, says he is sceptical because of the huge amount of energy that is needed to condense water.

Whisson says he is well aware that a large amount of energy is required to do the job.

"It's like boiling a kettle in reverse," he says.

But he is confident his wind turbine, still subject to patent applications and yet to be independently tested, is efficient enough.

"The wind turbine is a surprisingly good development. I'm surprised because it performs so well," says Whisson.

And he says the power generating part of the wind turbine can simply be increased to collect the wind power required for the condensation process.

"We've got unlimited power," he says.

But Reizes says wind turbines are so far only about 30% efficient at best and the energy arriving at them is very diffuse, requiring large devices to collect the energy.

"It may be a fantastic idea on paper and it looks as if it could work," he says.

"However, the thing may have to be so big to drive this device that it becomes impractical."

Drawing moisture from air

One thing seems more certain. If the system does work, it is unlikely to backfire on the environment, says Dr Michael Coughlan, of Australia's Bureau of Meteorology.

He says the amount of water that humans would use is trivial compared with the amount available in the atmosphere.

"If you can tap into it, then go for it, because you would do little to upset the hydrological cycle," says Coughlan.